--- In Diesel-RVs@yahoogroups.com, "david brady" <dmb993@...> wrote:
>
> Folks,
> Here's a hypothetical question for you. Assume the tire load tables
> spec that you should be running 100psi in your steer tires to
support your 10,000lb front end. We all know that the 100psi should
be set when the tire is cold. What if I install a realtime tire
inflation/deflation system that can alter the tire pressure as I
drive down the road. How should the pressures in the tire be
adjusted. If all that's required is 100psi to support 10,000 pounds,
then as the tire heats and the pressures rise, is it reasonable to
bleed of pressure back to the 100psi required to sustain the load?
>
> Thanks,
> David Brady
> Blue Bird, LXi
>
No, David, that's not how it works. Some military vehicles are
equipped with a "realtime tire inflation/deflation system" to allow
them to maintain traction OFF THE ROAD in conditions such as sand and
mud -- not to try to maintain a set pressure. If you were stuck in
sand, for example, deflating your motorhome tires down to 35-40 psi
might allow you to drive out of the sand, but if you drove on
pavement at that pressure, the tire would soon get hot enough to
actually catch fire!
I was running a service station back when tubeless tires were new on
the market. One day a customer on Highway 66 drove in to fill up
with gas, and he asked me to check his tires, which were hot. I
checked one tire, and it read about 36 psi, and he said, "Bleed it
off! Bleed it off!" I told him that if I bled it off, he would need
to air it back up when it cooled down, and if I bled it down to 32
psi, within a few miles the heat would bring it back up to 36 psi
again. The difference was how hot the tire would have to get in
order to build up to 36 psi.
He said, "That's a tubeless tire, and it'll blow out at 45 psi!" I
said I didn't know who told him that, but it wasn't true. When
someone brought in a tubeless car tire with a slow leak, I aired it
up to 100 psi and then ran water across the tire looking for leaks.
If I couldn't find a leak at 100 psi, then I would deflate the tire,
break down the beads and coat them with rubber cement and reinflated
the tire back up to 32 psi. I never had a comeback for a slow leak.
Like Russ said, I've seen wheels split from overloading, but I've
never seen a tire blow out from too much pressure.
Weigh your coach, then adjust your tire pressure for the load that
tire is carrying, and then check the pressure every week or two with
a gauge. You might need only 85-90 psi on your steer tires to carry
the load, and it will definitely ride better. On the highway, I
check my tires by pounding them with lug wrench (mostly to see if one
of my duals is low. You can't always tell by looking.). Listen for
the "ring" of a tire, and then if you
hear "boing," "boing," "boing," "thud," you'll know that particular
tire needs attention.
Ken Molloy
1994 Allegro Bay 37' DP with no toad
5.9 l Cummins 230 hp w/Allison M-3060
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